Preparation of beta branched primary alcohols

ABSTRACT

STRAIGHT-CHAIN, PARAFFINIC, PRIMARY ALCOHOLS SUCH AS N-DODECANOL) DIMERIZE TO FORM B-BRANCHED, PRIMARY ALCOHOLS, WHEN CONTACTED WITH A CATALYTIC QUANTITY OF THE THERMAL DECOMPOSITION PRODUCT OF SODIUM BISULFITE.

United States Patent 3,642,914 PREPARATION OF BETA BRANCHEID PRIMARY ALCOHOLS Lawrence C. Mitchell, Southfield, Mich., assignor to Ethyl Corporation, New York, N.Y. No Drawing. Filed Mar. 18, 1968, Ser. No. 714,073 Int. Cl. C07c 31/02 US. Cl. 260--642 4 Claims ABSTRACT OF THE DISCLOSURE Straight-chain, parafiinic, primary alcohols (such as n-dodecanol) dimerize to form [3-branched, primary alcohols, when contacted with a catalytic quantity of the thermal decomposition product of sodium bisulfite.

BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION I have discovered that the decomposition product obtained by heating NaHSO, also catalyzes the formation of branched form linear alcohols. This is illustrated by the following reaction equation for n-dodecanol. In the equation [cat] stands for the residual product obtained by heating NaH'SO [cat] 260 hrs.

In essence, my invention can be depicted by a preferred embodiment which is a process for preparing a fi-branched, primary alcohol, said process comprising dimerizing a straight-chain, parafiinic, primary alcohol having up to about sixteen carbon atoms; said process being conducted by contacting said straight-chain alcohol with a catalyst, said catalyst being the decomposition product obtained by heating NaHSO at a temperature of from 150 to 300 C., said process being carried out at a temperature of from 150 to 350 C. for a time sufiicient for said [i-branched alcohol to be formed; the mole ratio of said straight-chain alcohol to said catalyst being from 3 to l to 100 to 1. As illustrated by the above equation, I use the term B-branched to signify an alcohol havmg a branch on the carbon atom adjacent to the carbon atom in the carbinol group.

Branched alcohols are widely used intermediates. They are used in forming fuel and lube additives, the branched structure conferring enhanced solubility. In short, many of the alcohols produced by my process are known compounds, and they have the many utilities known for them.

In some instances my process forms (by-product) paraffins. These parafiins have 2n-l carbons (where the number of carbon atoms in the starting alcohol is n). These paraffins are useful; for example, they may be 3,642,914 Patented Feb. 15, 1972 ice dehydrogenated to form olefins; Kestutis A. Keblys, US. 3,293,318 and John M. McEuen, US. 3,322,849. The olefins may be subjected to ozonolysis-yielding acids, L. C. Mitchell, US. 3,362,971.

Furthermore, in some instances, my process forms byproduct sulfides. Thus, I have isolated (n-C H S when n-dodecanol is subjected to my process. Sulfides such as these are known and have the many utilities known for them.

DESCRIPTION OF PREFERRED EMBODIMENTS The alcohols used as starting materials in this process have the general formula c n pn I prefer to use straight-chain, paraffinic, primary alcohols having up to about 16 carbon atoms because these are readily available. However, there is no known size limitation. Thus, alcohols having 18, 20 or more carbon atoms can be employed.

The preferred alcohols are illustrated by the following non-limiting examples; ethanol, n-hexanol, n-heptanol, n-octanol, n-dodecanol, n-hexadecanol, and the like. Preferably, the alcohol has at least 4 carbon atoms. Two highly preferred alcohols are n-butanol and n-dodecanol.

The starting alcohol need not be pure. Mixtures of alcohols can be employed as starting materials. Thus, this process can be carried out using alcohol mixtures formed by Ziegler chain growth reactions employing olefin feeds such as ethylene.

As mentioned above, the catalyst used in the process of this invention is formed by heating sodium bisulfite. The catalyst, to a large extent, consists of sodium sulfite, probably formed by the following reaction sequence:

However, the exact composition of the catalyst is not known. In this regard, it is well to mention that a purchased sample of reagent grade sodium sulfite is much less reactive than a catalyst formed by decomposition of sodium bisulfite.

The catalyst can be formed in situ; in other words, it can be formed by decomposing the parent sulfite in the presence of the alcohol to be dimerized. The catalyst formation is conveniently conducted at atmospheric pressure and at a temperature sufiicient to form the catalyst. In general, the catalyst is prepared by heating it at temperatures of to about 400 C. and preferably at a temperature from to about 300 C. The catalyst formation is usually conducted over a period of from 0.5 to about 4 hours, and preferably by heating for 0.5 to 2 hours. Significantly, the catalyst can be reused as illustrated by an example which follows.

The alkali metals are considered substantially equivalent in many instances. This suggests that other alkali metal bisulfites such as lithium bisulfite and potassium bisulfite can be thermally decomposed to yield catalysts active in the process of this invention.

For purposes of this invention, a mole of catalyst is defined as the amount of catalyst formed by decomposition of one mole of parent bisulfite. As far as the amount of catalyst employed is concerned, it is only necessary to 3 use a catalytic quantity, that is, an amount sufficient to generate a reasonable amount of dimer product in a reasonable reaction time. In general, from 2 to 200 moles of starting alcohol are used for each mole of catalyst. A preferrled range of alcohol to catalyst is from 3 to 1 to 100 to The reaction temperature is not critical. It is only necessary to use a temperature which affords a reasonable amount of desired product within a reasonable reaction time. In general, temperaturw within the range of 125 to 400 C. are employed. A preferred temperature range is from 150 to 350 C.

The reaction pressure is not critical. In many instances, the reaction is conveniently carried out at atmospheric pressure. However, greater or lesser pressures can be used. Thus, the process can be conducted at superatmospheric pressures, say, to about 1000 atmospheres or higher. Such pressures can be employed when it is desired to conduct the reaction at a temperature above the normal boiling point of the starting alcohol.

I believe that the reaction course is enhanced by removal of water from the reaction system. This is conveniently done at atmospheric pressures by equipping the reaction vessel with a Dean-Stark trap or similar device. When conducting the reaction in an autoclave under superatmospheric pressure, water can be removed by continuous purging of the reaction zone with a gas such as nitrogen or argon. When using this technique, the gas is bled into the autoclave at a pressure slightly above the pressure within the reaction vessel, accompanied with simultaneous venting of eflluent gas. In many instances, it is best to introduce the gas stream below the liquid level in the autoclave.

The reaction time is not a truly independent variable since it is somewhat dependent on such parameters as tem perature, pressure, inherent reactivity of the starting alcohol and catalyst, etc. I have noted in a reaction conducted by forming the catalyst in situ that the formation of dimer product is subsequent to formation of the catalyst and that very little product was formed when the reaction was conducted for only an hours reflux after the catalyst was formed. (This is illustrated in an example following.) Consequently I prefer reaction times of from about 4 to about 48 hours, 1822 hours usually being sufiicient.

The reaction can be conducted by merely contacting the catalyst and the alcohol to be dimerized. Alternatively, it can be conducted by contacting the catalyst-alcohol mixture in the presence of other materials which are essentially inert to the reactant, product and catalyst. Thus, if desired, the reaction can be conducted in the presence of a reaction medium such as a solvent. Typical solvents which can be employed are paraflins, ethers, halogenated paraflins, amides and sulfones.

The following examples serve to illustrate the process of this invention but do not limit it.

EXAMPLE I Reaction of l-dodecanol with sodium bisulfite A 200 ml. round-bottom flask was charged with 100 ml. of l-dodecanol and 20 g. of sodium bisulfite. The flask was equipped with a Dean-Stark trap and reflux condenser. The mixture was heated to reflux under nitrogen. During heating bumping occurred as water distilled over along with a yellow solid that deposited on the condenser. As refluxing progressed it settled down and no more solid came over. After 22 hours the reaction mixture was cooled.

The mixture was filtered and the collected solid catalyst washed well with ether. The solid catalyst was dried in an evacuated desiccator; weight, 15.96 g. It was identified by IR and its X-ray powder pattern as mainly sodium sulfite. Theory for sodium sulfite is only 12.1 g. The IR showed it contained some organic material also.

The filtrate was stripped of ether; weight, 66.9 g. A 63.3 g. portion was distilled through a short Vigreaux.

Boiling point, mm. Weight, g.

Fraction Number:

Fraction 1 was identified as l-dodecanol by infrared analysis. Fractions 2 and 3 consisted of by-products. Fractions 4 and 5 were essentially 2-component mixtures with small amounts of impurities.

The two main components in Fraction 4 were separated by dissolving 1.0 ml. of the mixture in 10 ml. of methanol, cooling in a refrigerator, filtering the crystals, washing them with methanol and drying them in vacuo. The small amount of crystals isolated were identified as dodecyl-sulfide by IR, NMR and mass spec.: infrared (KBr): only C-H adsorptions; NMR (CCl 7.6-r [Tau] (triplet, 4 H), 8.71 (-40 H), 9.17 (triplet, 6 H); mass spec: m/e=370 (parent peak).

The filtrate from above was evaporated under a stream of nitrogen. The residue was identified as a B-branchedchain C saturated primary alcohol by IR, NMR and Mass spec: infrared (film), 3200 and 1170 cmr NMR (C01,): 6.61- (broad singlet (actually unresolved doublet), 2 H), 7.21- (singlet, 1 H, disappears on deuteratiorr), 8.7T (-41 H), 9.17 (triplet, 6 H); mass spec: m/e=354 (parent peak, proved by silanizing with Sil-Prep).

EXAMPLE II Reaction of dodecanol with sodium metabisulfite In a 300 ml. round bottom flask was placed ml. (83 g. 0.45 mole) of freshly distilled l-dodecanol and 18 g. (0.095 mole) of sodium metabisulfite. The flask was equipped with a Dean-Stark trap and reflux condenser.

The mixture was heated under nitrogen. Soon gas was evolved. After awhile the gas evolution stopped and a little gas adsorption occurred. Then a yellow solid and a little water began distilling. Eventually the alcohol refluxed and water distillation stopped. The mixture was refluxed for an hour and cooled.

The mixture in the Dean-Stark trap, weight 11.6 g., consisted of water (-1 ml.) and dodecanol plus minor impurities (VPC).

The reaction mixture was filtered. The collected solid was washed with ether and dried in vacuo; weight, 15.6 g. Infrared and X-ray analysis indicated the solid was mainly sodium sulfite containing a little organic material and amorphous material.

The filtrate plus washings was stripped on a rotary evaporator to remove the ether; weight, 66.5 g. VPC analysis showed it was mainly dodecanol plus some higher boiling components. However, the amount of high-boilers was much less than the previous example.

EXAMPLE III Reaction of dodecanol with recovered sodium sulfite 1 100 ml. round bottom flask was charged with 50 ml. (41 g., 0.22 mole) of distilled l-dodecanol and 8 g. (-.06 mole) of impure sodium sulfite recovered from Example I. The flask was equipped with a magnetic stirrer, Dean- Stark trap and reflux condenser. The stirred mixture was refluxed for 22 hours under nitrogen and cooled to room temperature.

The Dean-Stark trap contained water (-1 ml.) plus organic liquid and a little white solid; total weight, 11.33 g. The organic liquid was mainly dodecanol (VPC) with one other component of lesser retention time.

6 The reaction mixture was filtered. The collected solid it is desired that the invention be solely limited by the was washed with ether and dried in vacuo; weight, 7.39 g. lawful scope of the appended claims. Its IR spectrum was essentially the same as the starting What is claimed is: solid. 1. A process for preparing a p-branched primary al- The filtrate plus washings was stripped of ether; weight, 5 cohol contacting comprising contacting sodium bisulfite 28.8 g. A g. portion was distilled through a spinningwith a straight-chain, paraffinic primary alcohol having band column. up to about 16 carbon atoms and heating the resultant Bath temp, Ohd temp., Pressuremm. Weight, g. Remarks degrees degrees Cut Number 1 120160 60-94 0. 5 2. 66 2 147-161 94 0. 5 7. 79 3 161-247 100-156 0.5 3. 47 solidifies partly on standing. 4 258-270 156167 6 3. 86 Residue 1 78 Containssomesiliconegrease.

Cut No. 3 was filtered to give 2.83 g. of filtrate. The colmixture to 150 to 300 C. in an inert atmosphere; the lected solid was dissolved in pet. ether for VPC. VPCs mole ratio of said straight-chain alcohol to said bisulfite were run on all the distillation cuts. Cut Nos. 1 and 2 conbeing from 3 to 1 to 100 to 1.

sisted mainly of dodecanol-l. The major portion of the 2. The process of claim 1 wherein said straight-chain liquid from Cut No. 3 contained the same alcohol. The 20 alcohol is n-docecanol.

solid from Cut No. 3 had one major component which 3. The process of claim 2 wherein the mole ratio of was identified as n-tricosane by recrystallization from said straight-chain alcohol to said catalyst is about 5 to 1. ethanol and IR, NMR and mass spectrographic analysis. 4. The process of claim 1 wherein said straight-chain Cut No. 4 contained one major component which was alcohol is n-butanol.

the same C branched primary alcohol isolated in Ex- 25 ample I. References Cited Following the same procedure, the same alcohol is UNITED STATES PATENTS obtalned by conductlng the reaction at temperatures of 200 and 300 C. In a similar manner, n-butanol, n-heX- 2,457,866 1/1949 Carter anol, n-dodecanol, and n-hexadecanol are dimerized to 2762847 9/1956 91 et i form analogous products at temperatures of from 150 to 2 26O:642 300 C. These reactions are carried out using starting 3328470 6/1967 g at e a alcohol-catalyst ratios of from 3 to 1 to 100 to 1.

EXAMPLE IV BERNARD HELFIN, Primary Examiner Following the procedure of Example III, 100 ml. of I. E. EVANS, Assistant Examiner dodecanol-l and 12.0 grams of chemically pure sodium U S Cl X R sulfite were contacted. The reaction mixture yielded very little product; 252439; 260-583 R, 609 A, 676 R, 681

Having fully described this invention and its utilities 40 Po-ww UNITED STATES PATENT OFFICE (-s/ee) CERTIFICATE OF CORRECTION Patent No. ,6L2J9:LL Dated I Februarv 15. 1972 Inventor) Lawrence C.- Mitchell It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 5, "contacting" (both occurrences) should be deleted and admixing substituted for the second occurrence of "contacting" Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

